1518725 - Decide whether blobs should always get standalone textures to make them immune from eviction during shrinking

Status: RESOLVED WONTFIX

(Core :: Graphics: WebRender, enhancement, P2)

Description

[Glenn Watson [:gw]]

This can occur when the entire cache is cleared in maybe_reclaim_shared_cache_memory().

Comment 1

[Bobby Holley (:bholley)]

We basically need to ensure that anything with Eviction::Manual gets a standalone texture. I can write up a patch when I have a minute.

Comment 2

[Bobby Holley (:bholley)]

So to give a bit more context here - there are certain situations (specifically memory pressure and when the cache has been underutilized for too long) that we drop the entire shared cache texture and rebuild it. This has a bit of a mismatch with what we do for blobs, where we set the Eviction to Manual, because we don't want them getting evicted.

I thought this would be a correctness issue, but it looks like we do handle it [1]. That said, it looks like it requires synchronous blob rasterization, which is probably not great, but may be ok in the rare situations where we actually shrink the texture cache.

So I think this probably doesn't block, and may or may not be something we want to fix at all. Bumping for now, pending any disagreement from gw or nical.

[1] https://searchfox.org/mozilla-central/rev/5053031ba7621fa8f63f42de4c204ab3561e4e59/gfx/wr/webrender/src/resource_cache.rs#1064

Comment 3

[Glenn Watson [:gw]]

I don't think we plan to do this.